/*
 *  Copyright 2016 Alexey Andreev.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.teavm.model.util;

import org.teavm.model.BasicBlock;

/**
 * An object that receives information from {@link DominatorWalker}
 *
 * @param <T> type of state that can be saved for each visited node.
 */
public interface DominatorWalkerCallback<T> {
    default void setContext(DominatorWalkerContext context) {
    }

    /**
     * Called before visiting block. This method should tell whether this block and all of its descendant blocks
     * should be visited.
     */
    default boolean filter(BasicBlock block) {
        return true;
    }

    /**
     * Visits block and returns visit state. This state is saved by walker and then passed to
     * {@link #endVisit(BasicBlock, Object)} after all of this block's descendants visited.
     *
     * @return state that further will be passed to {@link #endVisit(BasicBlock, Object)}
     */
    T visit(BasicBlock block);

    default void endVisit(BasicBlock block, T state) {
    }
}
